I will introduce a family of matrices that emerge in connection with several
applied mathematics problems, including modeling electric potential on a
disk via Laplace equation, stationary Markov chains and color vision. I
called this matrix "magic Toeplitz matrix" because the sum of elements in
each row and column is the same. This matrix plays a central role in the
generalized Ohm's law on the disk with a circular resistivity and a finite
number of electrodes. Its connection to breast cancer diagnostic is
outlined. Further applications are discussed. The talk is accessible to
graduate and math major junior/senior undergraduate students.